1. Technical Field
The present disclosure is directed to a mask ROM.
2. Description of the Related Art
In systems that use a memory, in particular a mask read-only memory (ROM), for which some type of security is typically required, code data stored in a mask ROM should be prevented from being physically hacked.
In a conventional mask ROM, it is possible to analyze code data by monitoring an output of a sense amplifier, a bit line or a data line. Also, in the case of a mask ROM that uses a metal contact plug or via, it is possible to interpret code data by analyzing a contact plug layer or a via layer.